1. Field of the Invention
The invention relates to an assembly of a pneumatic tire and a rim having a band-like noise damper made of a sponge in a tire inner space, and to the noise damper used in the assembly.
2. Description of the Background Art
It has been known that one of tire noises is a road noise generated in the frequency region of from about 50 to about 400 Hz and that a resonance vibration (cavity resonance) of air occurring in the tire inner space is as a main cause. In order to reduce such a road noise, the applicant has offered an assembly (c) of a tire having a band-like noise damper (b) made of a sponge and extending in the tire circumferential direction in a tire inner space (a), which is shown in, for example, FIG. 22 and a rim (see, for example, JP-A No. 2003-252003). The noise damper (b) converts vibration energy of air in the tire inner space (a) to thermal energy to thereby, enable cavity resonance in the tire inner space (a) to effectively suppressed.
In a case where a pneumatic tire (d) is demounted from the rim (e), air in the tire inner space (a) is at first exhausted and then, a bead portion (d1), which is part of the tire (d), is pressed down into a well portion (e2) of the rim. Thereafter, a tire lever (f) is inserted into a clearance between the bead portion (d1) and a flange (e1) of the rim (e), and the tire lever (f) is inclined around the outer edge of the flange (e1) as a fulcrum to thereby take out the bead portion (d1) outward from the flange (e1).
A conventional noise damper (b), however, has a comparatively large thickness and a sectional shape thereof is rectangular or trapezoidal. That is, each side surface of the noise damper (b) is of a steep slope that rises high upwardly. Therefore, an inconvenience arises that the distal end of the tire lever (f) is, as shown with an imaginary line in FIG. 22, brought into contact with the noise damper (b) to thereby break the noise damper (b) or separate the noise damper (b) from the tire (d).
On the other hand, since the noise damper (b) made of a sponge is high in water absorptivity, there arises an unfavorable possibility that the sponge is wetted by rain or the like while a tire is stored or the tire and a rim are assembled. If a tire and a rim are assembled in a water absorption state, problems occur that the absorbed water adversely affects a weight balance to thereby cause tire vibrations, or permeates into rubber of the tire to thereby induce an internal damage. Therefore, in a case where a tire and a rim are assembled, it is necessary to remove water sufficiently, but a sponge having been once wetted is hard to be dried instantly, which makes its handling cumbersome.